Though it is often associated with computer devices, "hardware" is actually a term designating any type of physical component in a technological system. These components can come in the form of tools, equipment, or connective material holding a machine together. For example, latches, keys, and gears are all types of hardware, regardless of whether they are used in a mainframe or a doorframe. In addition, hardware may be constructed from a variety of materials, including metal or plastic. Hardware is also commonly used to connote military apparatuses, such as tanks, aircrafts, and missiles.